A 25-sided shape would have no parallel sides !
Well If you are looking for a four sided shape with no parallel sides it is called a trapezium.
A four sided shape with 2 parallel sides is called a trapezium. A four sided shape with 2 pairs of parallel sides is called a Parallelogram; This includes squares, rectangles and rhombi. If you want to find more about this you can check on google.
A four-sided shape in which only two sides are parallel is called a trapezoid. All two-dimensional, four-sided shapes are known as quadrilaterals.
A rectangle is a shape that has four sides with two parallel lines.
This figure is called a trapezoid or trapezium.
A trapezoid has two parallel sides.
2 parallel sides or 2 pairs of parallel sides?
A four-sided shape is a quadrilateral. With only one pair of parallel sides, it would be called a trapezoid (UK trapezium).